“As early as 1929 [Hitler] had publicly proposed that 700,000 of the ‘weakest’ Germans be ‘removed’ per year.” It seemed ridiculously implausible — even as “after-birth abortion” (infanticide) does in America today.

But ideas have consequences. Nietzsche was the John the Baptist of this Aryan anti-Christ. And the German race were to be the Übermenschen, while the Poles, the Jews, and the disabled were the Untermenschen.

With all eyes on the Polish front the “domestic nightmare could begin; the fog of war would cover a multitude of sins at home. . . In August 1939 every doctor and midwife in the country was notified that they must register all children born with genetic defects — retroactive to 1936. . . . In September the killing of these ‘defectives’ began. In the next few years five thousand small children were killed.

“As soon as the Polish campaign was under way, a number of adult patients deemed the least ‘fit’ were put on buses for these ‘transfers.’ The places to which these poor souls were transferred would murder them.

“Hitler’s memo on this subject was postdated September 1, to coincide with the beginning of the war. The rationale given for the killings was that the patients were taking up medical facilities and beds that should be used by soldiers wounded while fighting for the fatherland.

“The lessons learned in murdering these helpless patients helped the Nazis streamline their killing and cremation methods, which would culminate in the death camps, where hundreds of thousands and then millions of innocents were killed.” (Eric Metaxas, Bonhoeffer, 351–355).

Tell these stories to your children. Tell them with passion. Tell them with tears. Send your children into the world with their eyes sharpened with the bright light of history. Send them ready to name the academic Nietzsches for what they are. Send them with an unflinching Nie wieder! (Never again!) in their hearts.

The cross of Christ sanctified forever the sacred place of weakness in this world of self-exalting strength.

John Piper (@JohnPiper) is founder and teacher of desiringGod.org and chancellor of Bethlehem College & Seminary. For 33 years, he served as pastor of Bethlehem Baptist Church, Minneapolis, Minnesota. He is author of more than 50 books.